ABSTRACT
The key milestones are outlined and various examples of tunable solid-state lasers are mentioned. In particular, we concentrate on diffusion doping and discuss how the diffusion time and diffusion temperature influence the strength of the absorption bands. Different techniques for the determination of the diffusion constant are then described. Hence, concentration gradients were observed in samples prepared with this method. Possibility of uncontrolled contamination during the melting process, leading to unwanted passive losses, has also been pointed out. Chromium doping level of the samples can be adjusted easily by varying the diffusion temperature and/or the diffusion time. However, spatial inhomogeneities in chromium concentration may result due to the nature of the diffusion process. The concentration of the chromium ions inside the host varies with position, diffusion time, and diffusion temperature.
